1. Field of the Invention
This invention pertains to the field of urethane catalysts. More particularly, this invention relates to the use of certain amine derivatives as a urethane catalyst.
2. Description of the Prior Art
The use of a catalyst in preparing polyurethanes by the reaction of a polyisocyanate, a polyol and perhaps other ingredients is known. The catalyst is employed to promote at least two, and sometimes three major reactions that must proceed simultaneously and competitively at blanced rates during the process in order to provide polyurethanes with the desired physical characteristics. One reaction is a chain-extending isocyanate-hydroxyl reaction by which a hydroxyl-containing molecule is reacted with an isocyanat-containing molecule to form a urethane. This increases the viscosity of the mixture and provides a polyurethane containing secondary nitrogen atom in the urethane groups. A second reaction is a crosslinking isocyanate urethane reaction by which an isocyanate-containing molecule reacts with a urethane group containing a secondary nitrogen atom. The third reaction which may be involved is an isocyanate-water reaction by which an isocyanate-terminated molecule is extended and by which carbon dioxide is generated to blow or assist in the blowing of foam. This third reaction is not essential if an extraneous blowing agent, such as a halogenated, normally liquid hydrocarbon, carbon dioxide, etc., is employed, but is essential if all or even part of the gas for foam generation is to be generated by this in situ reaction (e.g. in the preparation of "one-shot" flexible polyurethane foams).
The reactions must proceed simultaneously at optimum balanced rates relative to each other in order to obtain a good foam structure. If carbon dioxide evolution is too rapid in comparison with chain extension, the foam will collapse. If the chain extension is too rapid in comparison with carbon dioxide evolution, foam rise will be restricted, resulting in a high density foam with a high percentage of poorly defined cells. The foam will not be stable in the absence of adequate crosslinking.
It has long been known that tertiary amines are effective for catalyzing the second crosslinking reaction. Typical amines of this type are found in U.S. Pat. Nos. 4,012,445; 3,925,268; 3,786,005; 4,011,223; 4,048,107; 4,038,210; 4,033,911; 4,026,840; 4,022,720 and 3,912,689.
U.S. Pat. No. 4,186,254 discloses a method for making polyurethane foams using a catalyst of the structure ##STR2##
Also U.S. Pat. No. 4,122,038 discloses the manufacture of polyurethane foams using a catalyst of the following structure: ##STR3##
This invention reveals a new amine compound which has structural similarity to the '254 and '038 patents just mentioned but which has a significantly higher activity.